Elevator installations are usually installed in a shaft in a building and serve for the transport of persons or goods. The car, which is movable in vertical direction in the shaft, is supported by support means in the form of, for example, cables or belts, wherein the support means are, for movement of the car, connected with a drive. Depending on the respective design of the elevator installation the car and/or a counterweight connected with the car by way of the support means is or are connected with the support means by way of one or more deflecting units. In the case of a 2:1 suspension, for example, one or two deflecting units are associated with the car and one deflecting unit is associated with the counterweight.
Deflecting units comprise one or more deflecting rollers which are mounted to be freely rotatable with use of, for example, roller bearings. The axle is fastened to a support at which the car or the counterweight is hung or suspended. This axle fastening can lead to problems with the deflecting units known for elevator installations. In rare cases it can happen that, for example, if maintenance has been deficient or omitted the deflecting roller no longer can freely rotate with respect to the axle, as a result of which high levels of torque between deflecting roller and axle can arise. This can have a negative effect on the axle fastening. In extreme cases the axle could migrate out of the support, which could lead to accidents.
A deflecting unit with a deflecting roller freely rotatable about an axis of rotation and mounted by way of axle on a support has become known from WO 2010/103165 A1 and has—with respect to a center plane running vertically relative to the axis of rotation of the deflecting roller—a mirror-symmetrical form of the axle. For axial securing, the axle, which is formed by a cylindrical body, has on two sides grooves in which the support engages directly or indirectly by way of a retaining part fastened to the support. The circumferential surface of the axle is interrupted by a planar section, which outwardly adjoins the respective groove and which is supported at a securing element screw-connected with the support and formed by a plate. The securing elements have the purpose of ensuring rotationally secure mounting of the axle. After failure of the rotational securing due to wear, according to a description in WO 2010/103165 the axle, which is firmly held by way of the grooves in the support, shall allow rotation of the axle. However, depending on the respective construction the desired axial securing is not provided, is insufficient or is achievable only by constructional solutions which are costly.